Autostereoscopic display

ABSTRACT

An autostereoscopic display device includes a device configured to provide collimated light and a dynamic beam deflector which is configured to scan a beam. The exit angle of the light emitted by pixels of the display array transmitted through a splitting screen is controlled and scanned by the dynamic beam deflector.

The invention relates to an autostereoscopic display device comprising adisplay array comprising a number of addressable pixels, a means foraddressing the pixels in the display array and a splitting screen infront of the display array.

An autostereoscopic display device of the type described in the openingparagraph is known form United States patent U.S. Pat. No. 6,275,254.

Basically, a three dimensional impression can be created by using stereopairs (two different images directed at the two eyes of the viewer),holographic techniques, or multiple planes in the displays. With themultiplanar techniques, a volumetric image is constructed, in which the2D pixels are replaced by so-called voxels in a 3d volume. Adisadvantage of most multiplanar displays is that the voxels producelight, but do not block it. This leads to transparent objects, givingquite literally a ghostly and unpleasant appearance to the displayedimages.

Stereoscopic displays do not suffer from this problem. There are severalways to produce stereo images. The images may be time multiplexed on a2D display, but this requires that the viewers wear glasses with e.g.LCD shutters. When the stereo images are displayed at the same time, theimages can be directed to the appropriate eye by using a head mounteddisplay, or by using polarized glasses (the images are then producedwith orthogonally polarized light). The glasses worn by the observereffectively route the views to each eye. Shutters or polarizer's in theglasses are synchronised to the frame rate to control the routing. Toprevent flicker, the frame rate must be doubled or the resolution halvedwith respect to the two dimensional equivalent image. A disadvantagewith such as system is that the two images produce only a limited “lookaround” capability. Furthermore, glasses have to be worn to produce anyeffect. This is unpleasant for those observers who are not familiar withwearing glasses and a potential problem for those already wearingglasses, since the extra pair of glasses do not always fit.

Instead of near the viewers eyes, the two stereo images can also besplit at the display screen by means of splitting screen such as alenticular screen or a parallax barrier. E.g. in FIGS. 3 and 4 of UnitedStates patent U.S. Pat. No. 6,275,254 the principle is shown.

Although these displays are autostereoscopic in the sense that nospecial glasses are required to view the 3D image, they usually workonly for one viewer at a fixed position in space. The viewing zone isvery narrow. Outside the viewing zone, the observer sees multiple imagesor a stereo inversion, leading to a very unpleasant view. In practicethis means that for many application, for instance in living rooms, theviewing zone is so small that the viewer has to be seated at oneparticular spot to be able to see a 3D image. Solution which offermulti-view images do so at the cost of resolution.

The device known from United States patent U.S. Pat. No. 6,275,254offers a solution to the narrow viewing zone problem by using a planarcathode ray tube type display having columns of pixels, and with aspecial magnet for sweeping electron beams to different parts of thecorresponding pixels, and having a lenticular lens screen having aplurality of cylindrical lenses each corresponding to a different columnof pixels. In this manner it is possible to create a multiviewautostereoscopic display.

Although it is possible to obtain a multiview autostereoscopic displaywith a relatively high resolution in the manner described in U.S. Pat.No. 6,275,254, it requires a highly specialised planar cathode ray tube.Planar cathode ray tubes, even apart from the use of a specialdeflection mechanism as necessary for the display device described inUnited States patent U.S. Pat. No. 6,275,254, have, although suchdevices have frequently been described in literature, never beensuccessful.

It is therefore an object of the invention to provide an alternative tothe known device.

To this end the device in accordance with the invention is characterizedin that the display device comprises a means for providing collimatedlight emitted by the pixels of the display array towards the splittingscreen, and in that the splitting screen is a dynamic splitting screen,and in that the device comprises means for controlling the dynamicsplitting screen for controlling the exit angle of the light emitted bypixels of the display array transmitted through the splitting screen.

Collimated light means, within the concept of the invention, light whichis confined to within a relatively narrow angle, typically less than 10degrees, preferably less than 5 degrees and most preferably withinapproximately 2 degrees. Within the framework of the invention“collimation” means collimation in at least one direction, the directionof scanning, not necessarily in two direction, i.e. not necessarily alsoin a direction perpendicular to the scanning direction. In practice thiswill often mean collimation in the horizontal direction (left-right),whereas collimation in a vertical direction (up-down) will or can bemuch less or not apparent.

By using collimated light entering the splitting screen, the light pathof the light coming into the splitting screen is substantially fixed, inparticular the direction and/or position vis-à-vis the splitting screenis fixed. The splitting screen is dynamic, i.e. it has optical elementswhose optical properties are controllable in such a manner that the exitangles of the light paths are controllable and scannable over a range ofexit angles by controllably changing the exit angle of the light emittedby pixels of the display array transmitted through the splitting screen.In this manner a multi-view, i.e. wide viewing zone for more than oneperson, stereoscopic display device is obtainable. By varying the exitangle the light of a particular pixel is in operation directed todifferent viewing zones. This is a fundamental difference with the knownmulti-view autostereoscopic devices since in these devices to eachviewing zone of the multiview viewing different pixels or parts ofpixels are assigned.

Collimating the light is a relatively simple operation, well known to aperson skilled in the art, which is applicable to many, if not all knownmatrix display devices, i.e. not requiring a specialized, as yetunsuccessful, display device. One can use a display array which initself already emits collimated light (e.g. display arrays based on oneor more lasers), or one can use a matrix such as an LCD or OLED displayarray, which normally provides a matrix of pixels emittingnon-collimated or diffuse light, and position in the light path beforethe splitting screen a collimator (e.g. a Fresnel lens or a plate withholes) to collimate the light. Such a collimator can be positionedbetween a continuous light source (e.g. the backlight of an LCD matrixdisplay) and a switchable spatial light modulator (e.g. the LCD array ofan LCD display device) or after the switchable light modulator. Using aPLED or OLED display array (of which devices the pixels emit light in awide range of angles) the collimator may be positioned between thesplitting screen and the PLED or OLED array. The collimator can be e.g.an array of lenses, e.g. Fresnel lenses, or a filter transmitting onlylight within a certain narrow angle range. An alternative is e.g. amultilayer interference filter positioned between the light source andthe splitting screen transmitting light only in a narrow forward anglerange, while reflecting light outside this range. In any of theseembodiments collimated light enters the splitting screen.

The scannable splitting screen scans the image, and sequentiallydisplays the image in a range of exit angles. By timing the displayedimage on the display array with the scan using the means for addressingthe pixels of the display screen, a multiview autostereoscopicdisplaying of images is achievable.

In a first class of embodiments the splitting screen is a lenticularlens screen having a plurality of cylindrical lenses arranged such inrespect to the pixels of the display array that the collimated light ofa pixel enters a lens off-axis, and the focal point of the lens iscontrollable. Since the collimated light enters the lens off-axis theexiting light exits the lens under a deflection angle. This deflectionangle is dependent on the focal point of the lens. By changing the focalpoint of the lens the angle of deflection (and thereby the exit angle)is controllable. This will sweep the light produced by the pixel over anexit angle range.

In embodiments of the invention the splitting screen comprises wettableliquid lenses, having a liquid lens array and electrodes and means toprovide voltage differences between the electrodes whereby the shape ofa wettable liquid lens is a function of the voltage difference overelectrodes. The change in shape of the wettable lens affect the exitangle.

The shape of a lens may be changed by changing the voltage differenceover electrodes. A substantial sweep (of ±30° to ±50°) is possible. Itis remarked that U.S. Pat. No. 5,717,453 describes the use of variablewettable lenses (or as named in U.S. Pat. No. 5,717,453 variable focusliquid lenses) for an autostereoscopic device. However, in this knowndevice to each point or pixel a variable lens is associated and the raysform each pixel are controlled to reach the eye at a predetermined anglecorresponding to the 3D depth desired for that pixel. The viewer isstill positioned at the same spot (i.e. the exit angle is not changed)but the focus is changed to give a depth perception. In this inventionthe off-axis entry of the light leads to a change of exit angle, i.e.sweep of the light over viewing zones.

Alternatively the variable lenses are solid lenses of a first material,embedded or surrounded by a second material, whereby the index ofrefraction of the first and/or second material is dependent on voltagesapplied on or over the first or second material. By changing the indexof refraction the focal point of the lens can be changed. This is a lesspreferred embodiment in respect of the previously described embodimentsince a relatively small change in focal point is possible, reducing thesweep.

In a second, preferred, class of embodiments of the device in accordancewith the invention, the splitting screen comprises a plurality ofvariable prisms and, associated with the variable prisms, electrodes forapplying voltage differences for varying the exit angle of collimatedlight being incident on the variable prisms.

“Variable prisms” within the concept of the invention means prisms ofwhich the angle of deflection of a light ray entering the prism at theside facing the pixel array is dynamically variable. This embodiment ispreferred since a somewhat larger sweep of angles (compared to wettablelenses) is possible, and because the restriction of entering off-axis isremoved, which allows for more freedom in design and accuracy.Furthermore the restriction on the collimation of the light are less fora variable prism than for an variable lens (i.e. a somewhat largervariation in entry angles may be allowed).

In embodiments of the invention the variable prisms are formed byvariable wetting prisms.

In variable wetting prisms the application of a voltage difference leadsto a change in the angle of the prism, changing the exit angle.

In embodiments of the invention the variable prisms are formed by solidprisms of a first material, embedded or surrounded by a second material,whereby the index of refraction of the first and/or second material isdependent on voltages applied on or over the first or second material.By changing the index of refraction the exit angle can be changed.

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

In the drawings:

FIG. 1 illustrates the basic principle of a lenticular screen splittingtwo stereo images.

FIG. 2 illustrates the basic principle of a parallax barrier splittingtwo stereo images.

FIGS. 3A and 3B illustrate the same principles as shown in U.S. Pat. No.6,275,254.

FIG. 4 illustrates the problem encountered with a basic parallax barrierdisplay.

FIGS. 5 and 6 illustrate known multi-view devices.

FIGS. 7A and 7B illustrate dynamic lenses and prism.

FIG. 8 illustrates a device in accordance with the invention havingdynamic lenses.

FIG. 9 illustrates a device in accordance with the invention havingdynamic prism.

FIG. 10 illustrates a further device in accordance with the inventionhaving dynamic prisms and a dynamic barrier layer.

The figures are not drawn to scale. Generally, identical components aredenoted by the same reference numerals in the figures.

FIG. 1 illustrates the basic principle of a lenticular screen splitting3 two stereo images 5 and 6. The vertical lines of two stereo images are(spatially) alternatingly displayed on, e.g., a spatial light modulator2 (e.g. a LCD) with a backlight 1. Together the back light and thespatial light modulator form a pixel array. The lens structure of thelenticular screen 3 directs the stereo image to the appropriate eye ofthe viewer.

FIG. 2 illustrates the basic principle of a parallax barrier splittingtwo stereo images. The vertical lines of two stereo images arealternatingly displayed on, e.g.; a spatial light modulator (e.g. a LCD)with a back light. The grating structure of the parallax barrier 7ensures that each eye of the viewer 4 sees the appropriate stereo image(5, 6).

FIG. 3A and 3B illustrate the same principles as shown in U.S. Pat. No.6,275,254.

In a conventional barrier auto-stereoscopic display system, a barrier 31is disposed in front of a display array 32. The left and right images ofa stereo pair of images are sliced into vertical strips. The strips 32Lof the left image and the strips 32R of the right image are alternatelydisposed on array 32. Slots 31A are formed in barrier 31. Slots 31A arepositioned so that the left eye 4L of an observer can see only strips32L of the left image and the right eye 4R can see only strips 32R ofthe right image of the pair. The observer reconstructs the full image inthree dimensions.

Referring now to FIG. 3B, barrier 31 is replaced by a lenticular lensscreen 33 having an array of vertical cylindrical lenses 33A eachcorresponding to a different pair of left and right image strips 32L and32R. In operation each lens directs the left eye 4L of an observer ontoa left image strip 32L and the right eye 4R of the observer onto a rightimage strip 32R.

FIG. 4 illustrates the problem of the basic stereoscopic device. Aviewer which is not seated within the right viewing zone is confused.The viewing zone is very narrow. Outside the viewing zone, the observersees multiple images or a stereo inversion, leading to a very unpleasantview. In practice this means that for many application, for instance inliving rooms, the viewing zone is so small that the viewer has to beseated at one particular spot only to be able to see anything. Forliving room use this is far from optimal since only one viewer can seethe 3D image and then only when seated on one spot.

It is possible, as shown in FIG. 6 of U.S. Pat. No. 6,275,254 to use foreach lens of the lenticular screen more than one vertical column ofdisplay elements. In this manner a multi-view display is possible.Schematically this is indicated in FIG. 5. To each lens 33A severalpixels (32C, 32D, 33E, 32F) are associated.

For the parallax barrier, a multiviewer display can be made by making itpossible to view many (columns of) pixels of the spatial light modulatorthrough the same slit of the barrier, as sketched in FIG. 6. Althoughthis will work, it is to be noted that the number of slits in respect ofthe number of pixels is greatly decreased in respect of FIG. 4, or viceversa the number of pixels per slit is greatly increased. The pixelswithin region 61 are associated with the slit 62 so the number of pixelsper slit is large.

However, in both solutions the number of directional views is increasedat the cost of resolution since a large number of columns of pixels isassociated with each lens or each barrier slit. These lenses and slitsshould be, in order to get a resolution comparable to the resolution forthe viewer in a device as shown in FIG. 4 relatively small and thus thismeans for instance that, for sub-millimetre resolution of the display,the pixels must be smaller than 10 microns (assuming 100 directionalviews). Besides the deterioration of resolution which is present forlenticular lenses and parallax barriers alike, the light transmissionthrough a parallax barrier is also greatly reduced, since only one ofabout 100 vertical lines of the barrier is transparent. This blocking of(more than) 99% of the light results in an extremely inefficientdisplay.

To increase the resolution the device disclosed in U.S. Pat. No.6,275,254 uses a specialized planar CRT device, in which, using specialmagnets electron beans are swept over pixels. Since the spot size in aCRT can be relatively small while yet giving a relatively large lightoutput the resolution can be kept at a reasonable value with areasonable light output. Thus the fundamental problem (i.e. therequirement of very small pixel size and problems with light output) isnot solved in U.S. Pat. No. 6,275,254 only a means for making verysmall, very bright spots is chosen. However, as said, this requires avery specialized, as yet unsuccessful (even without the special magnetswhich are necessary for the device disclosed in U.S. Pat. No. 6,275,254)type of planar CRT.

A partial solution could be to use a dynamic parallax barrier, i.e. abarrier in which the openings in the slits move. Such anautostereoscopic device is disclosed in the European patent applicationnr. EP 0 833 183 A1 e.g. in FIG. 36 of said patent application. In adynamic barrier layer (which can be constituted be an LCD shutter array)the transmitting line or lines are not fixed as in FIG. 6 but arescanned along the parallax barrier (e.g. from left to right or viceversa). For each position of the transmitting line of dynamic parallaxbarrier a different picture is displayed on the spatial light modulatorbehind the dynamic parallax barrier. This allows an increase ofresolution since in contrast to the device shown in FIG. 6 pixels arenot associated with a single slit. However the drawback is that theframe rate of the spatial light modulator is increased with the samefactor as the resolution gain (for example a factor of 100). This highframe rate limits the possible candidates for producing the image, andposes a problem for others. Besides the necessity of having to use ahigh frame rate, also an enormous light output is required, since thedynamic parallax barrier of EP 0 833 183 is as inefficient as a staticparallax barrier.

Thus the problem remains that a good 3D display should beautostereoscopic in the sense that no glasses are required yet have agood light output.

Furthermore it preferably has a “look-around” capability to avoidproblems with focussing of the eye and headaches. Preferably thiscapability should be intrinsic to the display, without additional meansfor tracking the head of the viewer. For TV applications, the displaymust also have a multi-viewer capability. Finally, the 3D display shouldalso be 2D compatible. The above autostereoscopic displays withmultiviewer capability can in principle be made by means of a lenticularscreen or a parallax barrier, but at the cost of a greatly reducedresolution.

To this end the device in accordance with the invention is characterizedin that the display device comprises a means for providing collimatedlight emitted by the pixels of the display array towards the splittingscreen, and in that the splitting screen is a dynamic splitting screen,and in that the device comprises means for controlling the dynamicsplitting screen for controlling the exit angle of the light emitted bypixels of the display array transmitted through the splitting screen.

The present invention provides an alternative path of solving theproblems. The splitting screen is dynamic and acts as a variabledeflector to deflect the light and thereby vary the exit angle of thelight emitted by the pixels. Thus the light of a pixel is swept overseveral viewing zones, and resolution can be maintained.

FIGS. 7A and 7B illustrates variable optical elements, such as lensesand prisms. The basic idea is that a variable lens, mirror, or prism canbe formed by the interface of two substances such as immiscible liquidswith different refractive indices. The shape of this interface ismanipulated by electrowetting, i.e. by varying the contact angle of theinterface to the boundary of the cell by means of an electrostaticpotential. The lay-out of an electrowetting lens and an electrowettingdeflector is given in FIGS. 7A and 7B wherein in FIG. 7A a variableelectrowetting lens 71 is shown. The focal strength depends on thecurvature of the meniscus between oil and water (73, 74), which isvaried through the potential difference between the water and the(insulated) electrodes at the side. An off-axis entering collimatedlight beam (i.e. with a relatively small variation in angle) isdeflected, depending on the curvature, two situations are shown, one(full lines) in which the light beam is deflected to the right (viewingzone A) and one in which the light beam is deflected to the left(viewing zone B). Thus a collimate light beam from one pixel can bedeflected over a angle range (indicated by the curve between the arrowsA and B. In FIG. 7B a variable electrowetting prism is schematicallyshown. The deflection angle can be varied by varying the orientation ofthe meniscus through the potentials V1 and V2 at the two sides of thecell. two situations are shown, one (full lines) in which the light beamis deflected to the right (viewing zone A) and one in which the lightbeam is deflected to the left (viewing zone B). Thus a collimate lightbeam from one pixel can be deflected over a angle range (indicated bythe curve between the arrows A and B.

A high-resolution multiviewer autostereoscopic display can thus beobtained with a dynamic lenticular screen, where the (static) cylinderlenses of the lenticular screen are replaced by variable, preferablyelectrowetting cylinder lenses with a variable strength. The deflectionangle may be varied by varying the strength of the lens. This isschematically and by means of example shown in FIG. 8. The exemplarydevice comprise a collimated backlight 1, a spatial light modulator 2, adynamic lenticular screen 3dyn, comprising dynamic lenses 71. Changingthe voltages changes, as schematically illustrated in FIG. 7A the exitangle α of the light beam, and thus the light is scanned over a widerange of angles. A drawback of this method is the increase in frame rateof the light modulator: for each dynamically addressed viewing angle, adifferent 2D image must be displayed on the modulator. An optimum may befound by exchanging spatial resolution for time resolution: e.g. 10modulator pixels per variable lens, each addressing 10 separate viewingangles per frame time, to obtain 100 viewing angles per display pixel.

Another option is to, as already schematically indicated in FIG. 7B, touse variable, preferably electrowetting, deflectors (flat interfaces)instead of variable lenses (curved menisci). A deflection angle of up to100° is possible by refraction, and up to 125° deflection is possible byreflection. A device having dynamic deflectors is sketched in FIG. 9. Inthis case, the light beams (formed by collimated backlight 1 and spatiallight modulator 2) are scanned over exit angles α by varying theorientation of the prism 72 formed in dynamic prism array 91 by changingthe orientation of the liquid interface. The same considerations holdwith regard to modulator frame rate and resolution: several pixels maybe grouped into one, each scanning a segment of viewing directions. Inthis way, resolution can be exchanged for a reduction of frame rate anddeflection angle.

The dynamic prism solution is preferred over the dynamic lens solution,since, the exact position of the beam is more restricted in dynamiclenses in which the beam has to be confined to an off-axis part of thelens than in the dynamic prism where the beam can use all or at leastmost of the prism.

The use of a parallax barrier enables a good spatial resolution incombination with a good angular resolution, however at the cost of ahigh modulator frame rate and a low efficiency as was explained above.The low efficiency can be greatly improved by using a collimated backlight in combination with a dynamic beam deflector 91 in combinationwith a dynamic parallax barrier 101, as sketched in FIG. 10. In thisdisplay, all the light from the modulator is aimed at a line that is inthe transmitting state. Hence much less light is lost at the barrier.For example, when the quality of the backlight and deflector system issuch that it produces light beams with a divergence of 5°, and theparallax barrier selects a viewing direction within 1°, about 20% of thelight is transmitted, instead of less than 1%, increasing the lightoutput by a factor of 20. The barrier is dynamic, i.e. only that part ofthe barrier is open which is useful (this can be done for instance withLCD's). Of course, also in this embodiment several compromises arepossible between spatial resolution (width of barrier line), angularresolution (number of modulator lines per barrier line), modulator framerate, and light efficiency. The devices as shown in FIG. 10 use adynamic parallax barrier, which in itself is known. However, using adynamic beam deflector 91 in combination with a dynamic parallax barrieroffers the possibility of a great increase in light output (of the orderof several times to an order of magnitude to even more) and that opensnew possibilities which hitherbefore could not be reached. The dynamicbeam deflector 91 and the dynamic parallax barrier 101 may be separatedby a glass plate and preferably attached to said glass plate at oppositeside the glass plate. Using a glass plate has the advantage of providinga sturdy construction and it allows a reduction of the distance betweenthe dynamic beam deflector and the dynamic parallax barrier, reducingthe depth of the device.

In short the invention can be described (with reference to e.g. FIG. 8)as follows:

An autostereoscopic display device comprises a means for providingcollimated light (1, 2) and a dynamic beam deflector (3dyn). By means ofthe dynamic beam deflector the beam is scanned. The exit angle of thelight emitted by pixels of the display array transmitted through thesplitting screen is controlled by the dynamic beam deflector (3dyn).

It will be clear that within the concept of the invention manyvariations are possible. For instance the lenses or prism may bevariably focussed or oriented through mechanical means. For example,flexible polymeric or elastomeric lenses may be compressed or relaxed soas to vary their shape and thereby the exit angle of the off-axisentering light. Alternatively liquid lenses or prisms in flexible casingmay be mechanically compressed or relaxed akin to the human eye.

1. An autostereoscopic display device including a display arraycomprising: a number of addressable pixels, means for addressing thepixels in the display array, a splitting screen in front of the displayarray, means for providing collimated light emitted by the pixels of thedisplay array towards the splitting screen, wherein the splitting screenis a dynamic splitting screen having variable lenses, and means forcontrolling the dynamic splitting screen for controlling an exit angleof light emitted through the splitting screen by changing voltage levelsapplied to two opposite sides of at least one of the variable lenses tochange an orientation of flat interfaces between two immiscible liquidsof the variable lenses so that different images are directed to two eyesof a viewer, wherein the two opposite sides are adjacent to an entryaxis of an entrance light entering the dynamic splitting screen, andwherein in a first voltage level changes the orientation to deflect thelight emitted through the splitting screen to a first side, and a secondvoltage level changes the orientation to deflect the light emittedthrough the splitting screen to a second side, wherein the first side isdifferent from the second side, and wherein the light deflect to thefirst side is directed to a right eye of the viewer, and the lightdeflect to the second side is directed to a left eye of the viewer. 2.The autostereoscopic display device as claimed in claim 1, wherein thesplitting screen is a lenticular lens screen having a plurality ofcylindrical lenses arranged such in respect to the pixels of the displayarray that the collimated light of a pixel enters a first lens of the aplurality of cylindrical lenses off-axis, and the focal point of thefirst lens is controllable.
 3. The autostereoscopic display device asclaimed in claim 1, wherein the splitting screen comprises liquid lenseshaving a liquid lens array and electrodes and means to provide voltagedifferences between the electrodes whereby a shape of a liquid lens is afunction of the voltage differences over electrodes.
 4. Theautostereoscopic display device as claimed in claim 1, wherein thesplitting screen comprises a plurality of variable prisms and,associated with the variable prisms, electrodes for applying voltagedifferences for varying an exit angle of collimated light being incidenton the variable prisms.
 5. The autostereoscopic display device asclaimed in claim 1, wherein the display device further comprises adynamic parallax barrier in front of the dynamic splitting screen. 6.The autostereoscopic display device of claim 1, wherein the two oppositesides are substantially parallel to the entry axis.
 7. A display devicecomprising: a plurality of pixels; and a plurality of variable lenses infront of the plurality of pixels for receiving light emitted by theplurality of pixels and output an exit light toward a viewer, at leastone lens of the plurality of variable lenses having a flat interfacebetween two immiscible liquids; wherein orientation of the flatinterface is changeable by changing voltage levels applied to twoopposite sides of the at least one lens so that different images aredirected to two eyes of the viewer, wherein the two opposite sides areadjacent to an entry axis of an entrance light entering the at least onelens, and wherein in a first voltage level changes the orientation todeflect light emitted through the plurality of pixels to a first side,and a second voltage level changes the orientation to deflect the lightto a second side, wherein the first side is different from the secondside, and wherein the light deflect to the first side is directed to aright eye of the viewer, and the light deflect to the second side isdirected to a left eye of the viewer.
 8. The display device of claim 7,wherein changing the orientation changes an exit angle of the exit lightemitted through the at least one lens.
 9. The display device of claim 7,further comprising a source of collimated light to provide thecollimated light to the plurality of variable lenses.
 10. The displaydevice of claim 7, further comprising a source to provide lightoff-center to the at least one lens.
 11. The display device of claim 7,wherein the orientation is changed by changing a voltage applied to theat least one lens.
 12. The display device of claim 7, wherein theplurality of variable lenses form an array.
 13. The display device ofclaim 7, wherein the two opposite sides are substantially parallel tothe entry axis.